双波长紫外分光光度法测定贝母中腺苷和胸苷的含量

将4种贝母的甲醇提取物经薄层色谱法粗分离后,直接用双波长紫外分光光度法测定其含量。结果表明,该方法线性关系好,腺苷和胸苷标准曲线的相关系数均为0.9999,同时也发现平贝、炉贝和伊贝中腺苷都占核苷总量60%以上,而浙贝中仅占约40%,提示贝母生药的抗凝血活性可能与贝母中核苷类化合物的种类和含量的差别有关。     

Influenza B virus reinfection

Four outbreaks of influenza B infection occurred in Houston, Texas in the years 1976-1984. In the Houston Family Study, age-related infection and illness rates in the recent two epidemics resembled those reported previously. A total of 118 persons, including 35 children followed from birth, were followed longitudinally through this entire period and 331 persons were studied through at least two outbreaks. Fifty-nine (88%) of 67 children studied for four outbreaks were infected and 25% had a second infection; about half of the adults had one infection but only one of 51 was reinfected. Infection rates were proportionally lower for those followed through 2-3 outbreaks. Those with documented infection were protected decreasingly over time against reinfection and associated illness in subsequent epidemics. Such protection decreased in efficacy from 65% after 2-3 years, to 46% after 4-5 years, and to no protection after seven years.     

Acute intracranial hemorrhage secondary to thrombocytopenia: CT appearances unaffected by absence of clot retraction.

PURPOSETo describe the in vivo CT appearance of acute intracerebral blood clots formed from anemic platelet-depleted blood.METHODSThree patients with intracerebral hemorrhage secondary only to thrombocytopenia were examined with CT within 2 1/2 hours after the onset of clinical symptoms.RESULTSThere were no unusual CT features found in the intracerebral hemorrhages of patients with only thrombocytopenia. Specifically, a hyperdense zone(s) surrounded by areas of decreased density was identified.CONCLUSIONClot retraction (which cannot occur in patients with severe thrombocytopenia) is not necessary for the CT appearance of acute intracerebral hemorrhage.     

Morphogenetic adaptation of the looping embryonic heart to altered mechanical loads.

The biophysical mechanisms that drive and regulate cardiac looping are not well understood, but mechanical forces likely play a central role. Previous studies have shown that cardiac torsion, which defines left-right directionality, is caused largely by forces exerted on the heart tube by a membrane called the splanchnopleure (SPL). Here we show that, when the SPL is removed from the embryonic chick heart, torsion is initially suppressed. Several hours later, however, normal torsion is restored. This delayed torsion coincides with increased myocardial stiffness, especially on the right side of the heart. Exposure to the myosin inhibitor Y-27632 suppressed both responses, suggesting that the delayed torsion is caused by an abnormal cytoskeletal contraction. This hypothesis is supported further by computational modeling. These results suggest that the looping embryonic heart has the ability to adapt to changes in the mechanical environment, which may play a regulatory role during morphogenesis.     

Calcium ionophore-induced acrosome reaction correlates with fertilization rates in vitro in patients with teratozoospermic semen

The aim of this study was to determine the relationship between calcium ionophore A23187-induced acrosome reaction (AR) and sperm fertilizing ability. Semen samples remaining after preparation for standard IVF were studied in 109 patients who had sperm concentrations > or =20 x 10(6)/ml. Ionophore-induced AR was performed on motile spermatozoa selected by centrifugation on a Percoll gradient. Semen analysis was performed using standard methods. Patients with higher (>50%, n = 76) fertilization rates had significantly higher ionophore-induced AR than patients with lower (<50%, n = 33) fertilization rates (49 +/- 14 versus 38 +/- 21%, P < 0.05). When the data from all patients were analysed by logistic regression, only the percentage sperm motility in insemination medium and ionophore-induced AR were significantly related to fertilization rates. Similar results were also obtained when the data from a subgroup of patients with poor (<15% normal) sperm morphology were analysed. However, when patients with normal sperm morphology > or =15% were analysed separately, only sperm count and the percentage of spermatozoa with progressive motility in semen were significantly related to fertilization rates. In conclusion, ionophore- induced AR was significantly related to fertilization rates in vitro mainly in patients with teratozoospermic semen. Tests for ionophore- induced AR may provide additional information about sperm fertilizing ability but may not indicate specific defects of the physiological AR.      

Detection of reactive oxygen species (ROS) and apoptosis in human fragmented embryos

In human in-vitro fertilization (IVF)-embryo transfer, the in-vitro culture environment differs from in-vivo conditions in that the oxygen concentration is higher, and in such conditions the mouse embryos show a higher concentration of reactive oxygen species (ROS) in simple culture media. ROS are believed to cause damage to cell membranes and DNA fragmentation in somatic cells. This study was conducted to ascertain the level of H2O2 concentration within embryos and the morphological features of cell damage induced by H2O2. A total of 62 human oocytes and embryos (31 fragmented, 15 non-fragmented embryos, 16 unfertilized oocytes) was obtained from the IVF-embryo transfer programme. The relative intensity of H2O2 concentrations within embryos was measured using 2',7'-dichlorodihydrofluorescein diacetate by Quanti cell 500 fluorescence imaging and DNA fragmentation was observed with transmission electron microscopy and an in-situ apoptosis detection kit. The H2O2 concentrations were significantly higher in fragmented embryos (72.21 +/- 9.62, mean +/- SEM) compared to non-fragmented embryos (31.30 +/- 3.50, P < 0.05) and unfertilized oocytes (30.75 +/- 2.67, P < 0.05). Apoptosis was observed only in fragmented embryos, and was absent in non-fragmented embryos. Electron microscopic findings confirmed apoptotic bodies and cytoplasmic condensation in the fragmented blastomeres. We conclude that there is a direct relationship between increased H2O2 concentration and apoptosis, and that further studies should be undertaken to confirm these findings.      

Epstein-Barr virus-associated B-cell proliferations of diverse clonal origins after bone marrow transplantation in a 12-year-old patient with severe combined immunodeficiency

A 12-year-old boy with severe combined immunodeficiency who had been kept in a gnotobiotic environment since birth received bone marrow from a histoincompatible sibling in an attempt to reconstitute immunologic function. To prevent graft versus host disease, the donor's marrow was treated in vitro with monoclonal antibody and complement to remove alloreactive T cells. Eighty days after transplantation, the patient had a systemic illness characterized by fever, thrombocytopenia, gastrointestinal pain, and bleeding; he died on the 124th post-transplantation day. Postmortem examination revealed multiple tumor-like B-cell proliferations, recipient in origin, in numerous organs. Epstein-Barr virus (EBV) was isolated from the patient's pharyngeal secretions; EBV nuclear antigen was found in spontaneously transformed peripheral-blood lymphocytes, inflammatory cells from peritoneal fluid, and bone marrow cells; and EBV genomes were discovered in all tumor tissues. The donor's serum showed evidence of past EBV infection. Analysis of cellular immunoglobulin and immunoglobulin gene DNA from the tumors indicated both monoclonal and oligoclonal B-cell proliferations. These findings provide evidence for the evolution of EBV-induced polyclonal activation of B cells to oligoclonal B-cell proliferation and finally to monoclonal B-cell lymphoma.     

Interchromosomal duplications of the adrenoleukodystrophy locus: a phenomenon of pericentromeric plasticity

A 9.7 kb segment encompassing exons 7-10 of the adrenoleukodystrophy (ALD) locus of the X chromosome has duplicated to specific locations near the pericentromeric regions of human chromosomes 2p11,10p11, 16p11 and 22q11. Comparative sequence analysis reveals 92-96% nucleotide identity, indicating that the autosomal ALD paralogs arose relatively recently during the course of higher primate evolution (5-10 million years ago). Analysis of sequences flanking the duplication region identifies the presence of an unusual GCTTTTTGC repeat which may be a sequence-specific integration site for the process of pericentromeric- directed transposition. The breakpoint sequence and phylogenetic analysis predict a two-step transposition model, in which a duplication from Xq28 to pericentromeric 2p11 occurred once, followed by a rapid distribution of a larger duplicon cassette among the pericentromeric regions. In addition to facilitating more effective mutation detection among ALD patients, these findings provide further insight into the molecular basis underlying a pericentromeric-directed mechanism for non- homologous interchromosomal exchange.